The present invention is directed to bicycle transmissions and, more particularly, to various features of an apparatus for assisting a speed change operation in a bicycle transmission.
Various devices have been developed to operate bicycle transmissions such as derailleurs and internal hub transmissions. Examples of such devices particularly suited to assist the operation of derailleur transmissions are shown in U.S. Pat. No. 5,400,675. Such devices typically include a first operating member such as a first lever and a second operating member such as a second lever. The first operating member typically activates a ratchet mechanism to wind a control cable against the biasing force of a return spring, and the second operating member typically activates the ratchet mechanism to unwind the control cable in accordance with the biasing force of the return spring. The ratchet mechanism usually includes a stop mechanism that prevents the control cable from unwinding all at once (because of the biasing force of the return spring) when the second operating member is operated from its home position to its release activating position. The stop mechanism usually has two stages of operation. The first stage occurs when the second operating member reaches the release activating position (usually at the end of its range of motion), and the second stage occurs when the second operating member moves some distance back from the release activating position toward its home position. This can cause uncertain operation when the second operating member is held near the release position and not fully returned to its home position.